Heat a large Dutch oven over medium-high heat with extra-virgin olive oil a couple of turns of the pan. Add the pancetta, if using, the onions and the garlic. Stir occasionally for 3 to 4 minutes, then add the potatoes and season with salt and pepper, to taste. Cover the pan and cook for 5 minutes more, stirring occasionally. Add the escarole and season with nutmeg, cover the pan and let wilt for 2 minutes. Stir in the stock and water and bring the soup to a boil. Reduce the heat and simmer 15 minutes for flavors to combine, adjust salt and pepper, to taste, and let cool. Store for a make-ahead meal. Bring the soup, covered, to a boil over medium-high heat. Add the peas and ditalini and cook to al dente, about 7 to 8 minutes. Turn off the heat and serve in shallow bowls garnished with pesto.
Put the herbs into food processor along with the nuts and grated garlic. Season with salt and pepper, to taste, then add the lemon zest, extra-virgin olive oil and the cheese. Pulse into a coarse paste, then transfer the pesto to storage container and drizzle the top with a thin layer of extra-virgin olive oil to retard browning. Cover and store in the refrigerator. Bring to room temp when ready to use.